Observations from the James Webb Space Telescope have prompted two independent studies to propose that carbon dioxide ice on Jupiter's moon Europa originates from its subsurface ocean. The findings provide new insights into the composition of Europa's internal ocean, which is considered a prime target in the search for extraterrestrial life.

Two studies suggest that the carbon dioxide on Europa's surface originates from the moon's internal ocean. Recent observations of Europa by the Webb Space Telescope indicate that the moon's carbon dioxide ice originates from its subsurface ocean, highlighting the abundance of carbon in this potential center of extraterrestrial life.

Using recent James Webb Space Telescope (JWST) observations of carbon dioxide (CO2) ice on Jupiter's moon Europa, a pair of independent studies suggest that the carbon dioxide originates from the icy body's subsurface ocean. The two research teams' findings provide new insights into the little-known composition of Europa's internal ocean.

Jupiter's moon Europa is thought to have a subsurface ocean of salty liquid water beneath a shell of solid water ice. Because of this, Europa is a prime target for the search for life elsewhere in the solar system. Assessing the potential habitability of this deep ocean depends on its chemical composition, including the abundance of elements essential to life such as carbon.

Previous research has identified the presence of solid carbon dioxide ice on Europa's surface, but it has not been possible to determine whether the carbon dioxide comes from a subsurface ocean, is struck by meteorites on the lunar surface, or is produced on the lunar surface through interactions with Jupiter's magnetosphere. Determining the source of carbon dioxide could constrain the chemical composition of Europa's internal ocean.

The Near Infrared Camera (NIRCam) on NASA's James Webb Space Telescope captured this image of the surface of Jupiter's moon Europa. Webber discovered carbon dioxide on the icy surface of Europa, which likely comes from the moon's subsurface ocean. This discovery has important implications for the potential habitability of Europa's ocean. Because satellites are brighter at shorter infrared wavelengths, they appear blue most of the time. The white features correspond to the chaotic terrains Povis-Riggio (left) and Tara-Riggio (center, right), showing enhanced surface carbon dioxide ice. Source: NASA, ESA, CSA, Gerónimo Villanueva (NASA-GSFC), Samantha K Trumbo (Cornell University), Gerónimo Villanueva (NASA-GSFC), Alyssa Pagan (STScI)

Analyzing carbon dioxide distribution on Europa

In two separate studies, researchers analyzed near-infrared spectra of carbon dioxide on Europa's surface obtained with JWST.

In one of the studies, Samantha Trumbo and Michael Brown used JWST data to map carbon dioxide distribution on Europa and found that the area with the highest carbon dioxide levels is in the Tara Regio - an area of ​​about 1,800 square kilometers dominated by "chaos terrain," material that has resurfaced after geological destruction.

According to the researchers, the amount of carbon dioxide found in this newly resurfaced region - some of the youngest topography on Europa's surface - suggests it came from an internal carbon source. This means that carbon dioxide was formed in Europa's underground oceans and brought to the surface on geologically recent time scales.

However, the authors said the possibility of carbon dioxide forming on the surface from marine organic matter or carbonates cannot be completely ruled out. Whatever the explanation, the underground ocean contains carbon.

The first image is a map of Europa's surface using the Near Infrared Camera (NIRCam) on NASA's James Webb Space Telescope, and the next three images are composition maps using data from Webb's Near Infrared Spectrometer Integrated Field Unit (NIRSpec/IFU). In the composition map, the white pixels correspond to carbon dioxide in the large-scale chaotic topography known as the Tara Regio (middle and right), and to partial carbon dioxide concentrations in the chaotic Powys Regio (left). The second and third images show evidence of crystallized carbon dioxide, while the fourth image shows the complex amorphous form of carbon dioxide. Source: NASA, ESA, CSA, Gerónimo Villanueva (NASA-GSFC), Samantha K Trumbo (Cornell University), Gerónimo Villanueva (NASA-GSFC), Alyssa Pagan (STScI)

Another study also found

In a separate study of the same JWST data, Geronimo Villanueva and colleagues found that carbon dioxide on Europa's surface is mixed with other compounds. The team also found that carbon dioxide is concentrated in the Tara region, and believe this indicates that the carbon on the moon's surface comes from within.

The authors measured the 12C/13C isotope ratio of the ice but were unable to distinguish between abiotic and biotic sources. In addition, the team searched for plumes of volatile materials that break through the moon's icy crust. While evidence of these features has been reported in previous studies, the authors did not detect any plume activity in JWST observations.

They believe plumes on Europa may be infrequent or sometimes not contain the volatile gases they searched for. The results of these two studies complement each other and strengthen the conclusion that Europa's subsurface ocean is rich in carbon.